For our new Druid friends, here's a link to my main macro thread in the Mods & Macros Forum. There are several good examples there. EB asked me to put up a few more specific ones, though, so here we go. First off, note that there are several basic ways to cast spells on allies, with advantages and disadvantages to each.

Target and cast
This is where you select the unit you want to cast on, then press or click the hotkey for the spell. This is the way most healers start out in WoW, but it's absolutely horrible for raid healing, where reaction time is key.
Advantage: requires no macros or addons.
Disadvantage: very slow. And I mean very slow.

Hotkey spells to specific targets
This method requires macros or an addon specifically designed for the purpose. Example of such a macro:

If you bind this to, say, F1, you can press F1 to cast Lifebloom on the indicated party member, Shift-F1 to cast Rejuvenation, Ctrl-F1 to cast Regrowth, etc. In a raid, you can't possibly bind enough keys to cover every raid member, and remembering which key goes to whom is next to impossible. Instead, you must edit your macros to target each of the tanks in turn, and you must do this every time your tanks change.

Mouseover + hotkey
This method of casting uses mouseover macros bound to keys for each of your healing spells. You hover your mouse over the target and press the key to cast the desired spell. What's great about this is that it requires no clicking, plus you can set up your macros to default to your target or yourself if no valid mouseover or target exists. It also requires no addons to implement. You need a good keyboard layout to handle this, though, or you'll find your hands getting bound up with your movement keys, which can be fatal in many raid encounters. Example macro:

Let's say this macro is on your "5" key. You hover your mouse over the person you want to heal and press 5 to cast Regrowth on that target. If you don't have a friendly unit under your mouse cursor, you will cast on your current target if it's friendly. Hold Alt (or whatever your designated self-cast key is) and you'll cast on yourself instead.

Advantage: great for non-clickers, no addon needed, works on units in the gamefield.
Disadvantage: still have to use the mouse to hover over your target, need good keyboard setup, uses a macro slot for every spell.

Click casting
This method depends solely or primarily on your mouse, and requires an addon to implement. All your healing spells are bound to primary or modified mouse clicks on your party/raid/target frames. Different addons implement it in different ways, so consult your manual. Some examples include:
* Clique, which allows you to directly bind any spell, macro, or macro text to any mouse click. Works with all unit frames, including the default Blizzard frames.
* Healbot, Grid, etc, which provide their own set of unit frames/clickable boxes and predefined schemes which you can modify.

Example: let's say you decide to bind Shift-left click to Healing Touch in Clique. To cast HT on a target, hold shift and click on that target. If you have Shift-right click bound to Abolish Poison, you hold Shift and right click on the desired unit.

Using an addon for click casting takes the emphasis away from your keyboard and puts it on your mouse. The only thing you need the keyboard for is to hold down Shift, Ctrl, or Alt as needed. However, it only works on unit frames in the UI - you can't use it to cast on units in the gamefield (3D world). Lastly, you're just another unit with this setup, so casting on yourself requires that you click on your own unit frame.

Advantage: removes almost all emphasis on the keyboard, no macro slots needed, extremely flexible
Disadvantage: requires mouse clicks, doesn't work on units in the gamefield, need to remember the modifier combos you set up.

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Now, here are some specific macros that are very useful.

Nature's Swiftness + Healing Touch (separate hotkey, mouseover targeting)
Use this when you want to have NS+HT on a separate hotkey from normal HT.

And never, ever, ever, ever, ever let me catch you EVER using healing touch in a raid fight situation. If you are using healing touch, you are not keeping up whatsoever with rolling lifeblooms across tanks/melee dps/caster dps (when called for) and therefore are not completing your most basic roll in raiding. /slap at you, sir, /slap at you.

I never used anything of the above... ever... it's not neccessary to just repeatedly hit "3" or "5" for lifebloom/rejuv across your targets. Even in 5-mans regrowth is only used sparingly... gawd. LTHoTheal, kkthxbai!!!!

Of course I don't HT while raid healing, except with NS, but Elvenbane asked me to put up some useful macros. Besides, most of my post has to do with casting techniques, not Druid healing in particular.

P.S.: I like typing. A lot. It's what I do when I'm bored at my job, which is typing... a lot. Programming code in this case.

Yeah, I only use HT with NS as a macro. It's an effective panic button; if I ever see a tank at less than 40% health for more than 4 or 5 seconds, I throw this on him. I can crit HT for 8k+ so it's a nice instant big heal and when it crits it's even better.